A ceramide is constituted of a sphingoid (a long-chain amino alcohol having 16 to 20 carbon atoms) and a fatty acid bonded to each other and a glycosphingolipid is the ceramide bonded with sugar. The glycosphingolipid is a main glycolipid of animals and is a substance which is localized mainly in a cell membrane. Moreover, it is understood that the ceramide is present as a lamella structure in the intercellular lipid of the stratum corneum of the skin, plays an important role as a water permeability barrier of the skin, and is useful for prevention of dry skin or prevention of aging skin (see Patent Document 1).
As a method for producing a ceramide, reported are a method for producing tetraacetyl phytosphingosine (TAPS) by a fermentation method using mutant strains of microorganisms (see Patent Document 1), a method for producing an optically active ceramide by transesterification of carboxylic acid esters in an alcohol solvent such as butanol (see Patent Document 2), and a method for producing N-linoleoylphytosphingosine by amidating linoleic acid and phytosphingosine in ethyl acetate using p-toluenesulfochloride (see Patent Document 3), for example. In addition, it is reported that a ceramide acylated by carboxylic acid having a hydroxyl group can be produced using carboxylic acid ester having a hydroxyl group by a method similar to that described in Patent Document 2 (see Patent Document 4).
In the method described in Patent Document 2, the crude ceramide recovered from the reactor is cooled and then the precipitated crystals are washed and dried with methanol, however, crystal separation efficiency is poor. In addition, since a butanol used as a solvent remains, it is very difficult to remove the butanol and/or butanol odor. Further, in the method described in Patent Document 3, ethyl acetate is used as a solvent and a cumbersome washing procedure needs to be repeated after the reaction. Moreover, the yield is also very low and thus the method is not considered as an industrially advantageous method. In the method described in Patent Document 4, recrystallization is carried out using methanol and thus the method is also not considered as an industrially advantageous method.
As described above, there has not been established yet an industrially advantageous method which enables to produce a ceramide having high purity in large quantities.